There is plenty of sound advice and exemplary design available to guide designers and developers when integrating sustainable urban drainage systems (SuDS) and make this an opportunity to add to the character of a place.
The excellent diagram (above) from Planning for SuDS – making it happen published by CIRA in 2010 shows the range of ways SuDS can be integrated in the more formal or urban edges of a scheme by being integrated in paving, tree pits, rain gardens and roofs or running alongside streets in rills, bioretention strips or infiltration trenches. It shows how SuDS can provide contrasting spaces such as filter strips, naturalised swales, wildlife and wetland areas. Advice about the appropriate assembly of components is continued in more detail in the document with illustrations of the best components to use for high, medium and low density development and descriptions of how to embed SuDS in Design Codes or Retrofit into existing streets and spaces.
The authors of Planning for SuDS identify the “need to embrace water management as an opportunity” and advise design teams to consider the benefits and opportunities early on. A good scheme will be compatible with the landscape and integrated with the overall design strategy providing multiple benefits, for example, drainage and public open space or car parking. As well as managing flood risk benefits could include improved; water quality, amenity and biodiversity, water resources and recreation and education for communities. The benefits to developers in integrating SuDS are the reduction of maintenance costs associated with heavily engineered drainage and a possible increase the value of nearby homes.
Some important design principles are that sustainable urban drainage (SUDS) should mimic natural drainage, control water at its source and use sequence of components to manage flows of water and improve water quality. They note that: SUDS mimic natural drainage patterns by:
- storing runoff and releasing it slowly (attenuation)
- allowing water to soak into the ground (infiltration)
- filtering out pollutants
- allowing sediments to settle out by controlling the flow of the water
- creating attractive environments for people and wildlife.
Focusing on SUDS strategies for urban design projects the most illuminating case studies featuring in this and other more recent guidance are:
- Upton, Northamptonshire – which set out a design code for two street types integrating SUDS, one with SUDS at the centre and another with SUDS to one side with a footpath to the inside.
- Cambourne Pool Redruth Surface Water Management Plan (SWMP) – where a design approach has been developed across an area with the strategic integration of swales or leats to open up new areas for development.
- Malmo, Sweden and Reiselfeld, Feiburg, Germany are widely cited as good examples because of the bold way they integrate SuDS bringing water and wildlife features close to homes. The indefatigable Essex County Council have produced a design guide illustrated by these examples from Malmo and Reiselfeld and expanding on the advice in ‘making it happen’ with Essex focused case studies.
Dickie, S, McKay, G, Ions, L, Shaffer, P – Planning for SuDS – making it happen, CIRIA, 2010 http://www.eastcambs.gov.uk/sites/default/files/C687%20Planning%20for%20suds.pdf.pdf
Upton Design Codes V2, Northampton Borough Council, 2005
Nicholls, D, Cornwall County Council – Surface Water Drainage and Green Infrastructure
Sustainable Drainage Systems, Essex County Council, 2014
See also ongoing archive of case studies at Susdrain: